Low cost and sanitary efficient method that creates two different treatment zones in large water bodies to facilitate direct contact recreational activities

ABSTRACT

A treatment for a large body of water to make the water suitable for recreational purposes is disclosed. A sedimentation zone and a dissipation zone are designated in the water body. A disinfection method based on a CT index and a flocculant composition are utilized in the sedimentation zone to aid in the settling of different microorganisms and/or contaminants. Also, the water in the sedimentation zone is minimally disturbed to facilitate the sedimentation process. A permanent chlorine residual is maintained in the dissipation zone by adding an efficient amount of a chlorine disinfectant such that at least a 0.5 mg/L free chlorine level is maintained in the water volume. Water is injected into the dissipation zone by means of one or more inlet nozzles. Along with natural currents produced by winds and water temperature differences, a water dissipation pattern from within the dissipation zone into the sedimentation zone is generated.

FIELD OF THE INVENTION

The present invention relates generally to treating a large body ofwater in order to make the water suitable for recreational purposes;more specifically for treating the water using a low cost sanitarysystem and method to minimize the risk of growth of microorganisms suchas bacteria, protozoa, amoebas, microalgae and parasites, amongstothers, thus solving the inefficiencies of current methods and systemsin an innovative manner and at low costs. More specifically, theinvention relates to a low cost and sanitary efficient system and methodthat creates two different treatment zones in large water bodies tofacilitate direct contact recreational activities.

BACKGROUND OF THE INVENTION

Conventional swimming pool technology has been used and applied as thestandard water treatment for small sized recreational water bodies fordecades. However, such swimming pool technology has shown to beinefficient in the treatment and removal of several microorganisms fromrelatively small water bodies.

On the other hand, larger water bodies, like lakes used for swimming(hereafter referred to as “swimming lakes”) with higher dilutioncapacities have also had problems and have been inefficient in theinactivation and removal of some microorganisms, regardless of whetherthe water body is periodically treated or is untreated. Furthermore,conventional swimming pool technology when applied to such large waterbodies requires large capital costs, and requires large amounts ofenergy and chemicals to complete its operation and maintenance. Theseresulting costs make use of conventional technology of swimming poolsvery expensive when applied to large water bodies.

In general, recreational water bodies, such as swimming pools and largerwater bodies like swimming lakes, are always prone to be contaminated bymicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites, amongst others, which can create risks for bathers that usesuch water bodies for swimming, bathing, and for other direct contactrecreational uses.

A. Swimming Pools

For decades, swimming pool technology has been the most used watertreatment technology for small water bodies used for recreationalswimming purposes. Over this time, various health entities from aroundthe world have adopted regulations concerning the water treatment inorder to regulate minimum health standards for swimming pools.

Conventional swimming pool technology essentially requires a permanentdisinfection of the complete water volume to maintain a high ORP(Oxidation Reduction Potential) or disinfectant concentration, such asfree chlorine level on the water permanently. In addition, filtration ofthe complete water volume between one to six times per day (generallyfour times per day) is required to remove all suspended particles andcontaminants from such water volume.

However, it is important to understand that, contrary to popular belief,conventional pool disinfection technology does not kill all germs ormicroorganisms instantly. Instead, there are chlorine resistantmicroorganisms that may survive in chlorinated pool water and triggerRecreational Water Illnesses (hereafter referred to as “RWIs”). Eventhough there are certain bacteria that are killed within seconds withnormal swimming pool disinfection levels, there are many microorganismsthat have high tolerance to chlorine or other disinfectants. Thesemicroorganisms can survive for many days after a contamination event hasoccurred in the pool, since swimming pool disinfection treatment is notdesigned to kill all such microorganisms. One microorganism that ishighly resistant to conventional swimming pool disinfection technologiesis, for example, Cryptosporidium. This is an important cause of RWIs,especially in treated water bodies such as swimming pools, as previouslydiscussed. In fact, several studies show that free chlorine levels ofabout 1-3 ppm (such as the ones found in conventionally treated swimmingpools), can take more than 10 days to inactivate 99.9% ofCryptosporidium oocysts, as such microorganism is highly resistant toconventional swimming pool disinfection methods. Therefore, many bathersmay swim in a pool treated according to the pertinent regulations forswimming pool disinfection standards during that 10-day period and beexposed to infection by such microorganism.

Additionally, with respect to conventional pool filtration technology,generally sand filters are capable of filtering out particles in thesize range of down to 20-25 microns and cartridge filters are typicallycapable of removing particles in the size range down to 5-10 microns.But, by way of example, Cryptosporidium oocysts are approximately 4-6microns in size. This makes them very difficult to remove byconventional pool filtration with the commonly used filters being ableto remove only about 25% of oocysts per passage through the filter.

Based on the foregoing, it will be appreciated that when there is acontamination event in a pool, the disinfection and filtration systemsare not prepared for removing such microorganisms. Traditionaldisinfection is not enough to inactivate or kill such microorganisms,and the filtration system is not suitable for removing them from thewater in an appropriate timeframe that ensures that people will notbecome infected once the contamination takes place. In particular, dueto conventional swimming pool technologies requiring filtering thecomplete volume of water in the pool—which is a time consuming processthat does not even allow the complete filtering of all oocysts in anappropriate timeframe—together with the fact that chlorine may notinactivate all oocysts of certain microorganisms in a period shorterthan 10 days. Accordingly, if a contamination event occurs in the pool,such microorganisms may go undetected and infect many bathers before itis properly treated and eliminated from the pool water.

Therefore, swimming pools are prone to RWIs triggered by microorganismssuch as bacteria, protozoa, amoebas, microalgae and parasites, amongstothers present in the water which can have high resistance toconventional swimming pool water treatment methods, and therefore canpotentially reach bathers either by swallowing the water, breathing there-suspended microorganisms, or simply by having direct contact with thewater.

One study from the United States Centers for Disease Control andPrevention (CDC) summarized 90 reports of recreational water illnessesoutbreaks that occurred during 2011 and 2012 from 32 states and PuertoRico, where 69 outbreaks (76.6%) were found in conventionally treatedswimming pools. Additionally, a 2007 study from the CDC summarized theoverall 78 recreational water illnesses outbreaks reports that occurredduring 2005-2006, which accounted for illnesses occurring in 4,412people, resulting in 116 hospitalizations and five deaths. Of those 78outbreak reports, 31 (40%) were caused by Cryptosporidium. Another studyshowed that in June 2003, an outbreak of Giardia intestinalis started ata Massachusetts membership club pool, which resulted in 149 cases,including cases of secondary person-to-person transmission. Also, inJuly 2003, a Cryptosporidium outbreak spread in multiple Kansas poolsand day care centers and resulted in 617 cases. This last outbreak wasthe largest recreational water outbreak during 2003-2004. Further, inJuly 2004, an outbreak of Cryptosporidium in a community pool in Ohiocaused gastroenteritis in 160 people from three counties, and in August2004, employees ill with gastroenteritis at a California water parkcontinued performing working and recreational activities in the pools,resulting in a Cryptosporidium outbreak that involved 336 people withrelated illnesses.

Further, in 2008, the CDC reported that RWIs cases caused byCryptosporidium in the U.S. had tripled since 2004. However, thisincrease may have been influenced by more advanced detection methods,e.g., meaning that previous cases may have existed but went undetected.More recently, data collected during 2013-2014 from the CDC indicatesthat there were more than 71 outbreak cases from swimming pools reportedin the U.S., resulting in more than 950 cases. From 2000-2014, more than450 outbreaks have been reported, resulting in more than 27,000 cases,where more than half of such cases were due to Cryptosporidium.

The above described cases reinforce the fact that some microorganismssuch as Cryptosporidium and Giardia, among others, are not eliminatedeffectively through conventional swimming pool treatment methods orsystems. Therefore, while is a common belief that RWIs are a risk onlyin untreated water bodies, most of the cases where RWIs have resulted inseveral people becoming ill have taken place in conventionally treatedwater bodies such as swimming pools, which highlights the need ofimproved methods and systems to treat and maintain water bodies forrecreational purposes.

In addition to contamination due to microorganisms such asCryptosporidium and Giardia, swimming pools are prone to RWIs caused byamoebas present in the water body. For example, a 2003 study performedin Santiago, Chile found that five out of eight public swimming poolshad free living amoebas during the summer period, and that NaegleriaFowleri and Acanthoamoebas were present in 36.3% of the samples.Further, such study reported that one of said public swimming poolswhere no free living amoebas or microorganism were found, had anextremely high chlorine concentration which made the surrounding airunbreathable and caused eye irritation (especially because it was anindoor pool with poor air circulation).

More recently, in Spain, a 10-year-old girl from the province of Toledorecovered from the first case recorded in Spain of primary amoebicencephalitis (PAM) caused by Naegleria Fowleri, which was contracted ina public swimming pool treated and maintained with standard swimmingpool technology. Primary amoebic meningitis (PAM) is an extremelyaggressive disease that causes severe headache, fever and neck stiffnessfor several days and that leads to death in 97% of detected cases. Thiscase astonished doctors and health officials because the public swimmingpool in which the girl contracted the disease complied both with thechlorine levels and filtration standards that are considered safe.

Currently, if a contamination event of these types occurs in a swimmingpool, there are generally one of two outcomes:

-   -   If the contamination event goes undetected, which usually        happens, then the microorganisms will remain and spread in the        water, potentially infecting many bathers (even though the water        is being treated by the conventional pool system), which means        that there could be more than 10 days of exposure of bathers to        the dangerous microorganisms. Also, as emphasized before,        conventional pool filtration systems take a long time to remove        oocysts from the water since there is partial filtration, and in        some cases due to their sizes, the oocysts cannot be removed at        all.    -   If the contamination event is detected, in order to inactivate        and remove oocysts it is necessary to close the pool for several        days and sometimes even drain the entire complete pool volume,        which rarely happens. Alternatively, the swimming pool can go        through a process of hyperchlorination, which requires an        extremely high chlorine concentration that as described above,        can make the surrounding air unbreathable as well as causing eye        and skin irritation.

In conclusion, conventional swimming pool technologies, which combinedisinfection and filtration processes are not prepared for treating somemicroorganisms, like Cryptosporidium and Giardia amongst others, whichmakes it difficult to ensure that the water, which is used for directrecreational purposes, is free of disease-causing microorganisms.Conventional pool systems are slow or ineffective in eliminatingmicroorganisms of these types, even though they comply with the requiredlocal regulations.

B. Larger Water Bodies

As mentioned above, there are also larger water bodies, such as swimminglakes used for direct contact purposes, that are somewhat treated. Thesewater bodies are also prone to high risks associated to the presence ofmicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites, amongst others. In some cases, fatalities occur after aperson becomes infected.

Generally, such large water bodies are partially treated using methodsthat essentially consist of reduced applications of conventionalswimming pool technologies. Thus, when these water bodies are treated,the disinfectant levels and filtration levels are typically much lowerthan required in conventional swimming pools. For example, instead ofmaintaining a permanent 1 ppm of free chlorine in the complete watervolume (as a conventional swimming pool), such large water bodiesmaintain much lower levels and not necessarily permanently, and insteadof filtering the complete water volume from four to six times per day(as it is required in a conventional swimming pool), the water volume ispartially filtered and/or with less periodicity. This partialdisinfection and filtration is applied in such large water bodies mainlydue to economic reasons, since the use of conventional swimming pooltechnologies in large water bodies would require very high capacitysystems and equipment costs, as well as high operation costs related tothe large amount of required chemicals and electricity for filtrationpurposes.

It is also important to note that such partially treated swimming lakesgenerally have poor water clarity. This is in contrast to thetransparency and crystal clear conditions of conventional swimmingpools, which is mainly the result of a partial filtration of the watervolume.

When dealing with confined recreational water bodies, such as partiallytreated larger man-made lakes and lagoons, or similar, it is importantto note that when they are not treated with conventional swimming pooltechnology, important sanitary risks might be generated. For example,there have been many accidents caused by dangerous microorganisms inconfined man-made large water bodies that were not treated usingtraditional swimming pool technologies, but were instead using a partialapplication of the technology.

A representative case is the one at Disney's River County, where an11-year-old boy died from Naegleria Fowleri, which he contracted whileswimming in their artificial lagoon. Another case happened at NorthCarolina's National Whitewater Center, where an 18-year-old woman diedabout a week after contracting the amoeba while rafting at the center.

Another recent accident happened in an artificial surf lake located inWaco, Tex., which did not use conventional pool technology but insteadused a partial disinfection and filtration. In this accident, a29-year-old surfer contracted the Naegleria Fowleri amoeba and died onSep. 21, 2018. Even though this accident had fatal consequences, whenthe water quality analyses were performed on Sep. 27, 2018, the amoebawas not found in the surf lake, but was found in nearby water bodies.Therefore, it is very important to highlight that a simple water qualityanalysis is usually not adequate for preventing these types ofaccidents, since these microorganisms can be present in specific sectorswithin the water bodies and/or located in corners.

As an indication of the size of the problem, there have been more than140 registered cases in the U.S. of the Naegleria Fowleri amoeba, with a97% mortality rate.

The Naegleria Fowleri enters the organism through the nose, from whereit travels to the central nervous system and generates an acute braininflammation and eventually leading to a Primary Meningoencephalitis(PAM), a brain infection that leads to the destruction of brain tissue.For this reason it is sometimes referred to as the “brain eatingamoeba”. Meningoencephalitis has an incubation period of between two andeight days, and in almost all cases results in the death of the infectedpatient.

Acanthoamoebas, on the other hand, enter the human body through the eyesor skin cuts, travelling to the central nervous system and with anincubation period of only a few days. In the latter case, most of casesend with a fatal outcome.

Both amoebas and acanthoamoebas are particularly dangerous where theyare present in water bodies having strong currents or a constant watermovement that generates a resuspension of sediments accumulated on thebottom surface of the water bodies. The resuspension increases thechances for the bacteria to reach the nose and eyes of bathers.

Monitoring the amoebas through water quality analysis is extremelycomplex and requires specific knowledge. Also, it is not enough toperform a few water samples in different locations within the waterbodies, as such analysis would not help to conclude the same results forother locations as previously mentioned. Such amoebas can be present incertain locations within the water bodies, hidden in corners or inbottom sediments. Therefore, the detection of these amoeba requiretraining, specific analysis and controls—all of which illustrate theneed for a system and method for properly treat recreational useswimming lakes to avoid or minimize such risks.

Therefore, today there are no methods or systems that provide completesanitary safety in conventional swimming pools or in partially treatedlarger water bodies that are used for recreational purposes.Conventional systems, even for swimming pools, would require very highlevels of disinfectants, which apart from being extremely costconsuming, can generate a toxic environment and non-safe conditions forbathers and bystanders. In addition, it has been shown that even whenall the standards that are generally considered safe in a swimming poolare met, RWI's may still occur.

C. Disinfection Index

The patterns and requirements through which swimming pools or largerwater bodies are treated and maintained, are conventional swimming poolrequirements, and bacteriological standards from the U.S.E.P.A., amongothers. However, these standards may sometimes not be enough toguarantee that there will be no sanitary risks due to the presence ofmicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites amongst others in the water.

One manner of applying proper disinfection to inactivate differentmicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites amongst others is the use of the CT index. This index resultsfrom a specific concentration of a disinfectant “C” and the amount oftime “T” that the disinfectant is in contact with the water at suchspecific concentration in order to achieve a suitable disinfection. TheCT index is therefore determined by multiplying both values, as may beseen in the following equation:

${CT} = {{Concentration}\mspace{14mu}{of}\mspace{14mu}{{disinfectant}\mspace{11mu}\lbrack \frac{mg}{L} \rbrack} \times {Contact}\mspace{14mu}{{Time}\mspace{14mu}\lbrack \min \rbrack}}$

Different CT values allow for the inactivation of differentmicroorganisms, parasites, and protozoa, based on the type ofdisinfectant used, the temperature and pH of the water, and the level ofinactivation required. The following Table 1 illustrates CT values forthe inactivation of microorganisms.

TABLE 1 Disin- fectant Inactiva- tion Tempera- ture${CT}\mspace{14mu}{{Value}\mspace{11mu}\lbrack {\frac{mg}{L} \times \min} \rbrack}$Giardia Cysts Ozone 1 log 10° C. 0.48 (6 < pH < 9) Giardia Cysts Ozone 1log 25° C. 0.16 (6 < pH < 9) Giardia Cysts Chlorine 1 log 10° C. 112(For pH = 7) Giardia Cysts Chlorine 1 log 10° C. 162 (For pH = 8)Cryptosporidium Chlorine 3 log 25° C. 15,300 (pH < 7.5) NaegleriaFowleri Chlorine 3 log 25° C. 9 (For pH 7.5) (Trophozoites) NaegleriaFowleri Chlorine 3 log 25° C. 23 (For pH 9) (Trophozoites) NaegleriaFowleri Chlorine 3 log 25° C. 42 (For pH 7.5) (Cysts) Naegleria FowleriChlorine 3 log 25° C. 50 (For pH 9) (Cysts)

Inactivation is measured as 1 log, 2 log, 3 log or 4 log, as illustratedin the following Table 2:

TABLE 2 1 log 90% Inactivation 2 log 99% Inactivation 3 log 99.9%Inactivation 4 log 99.99% Inactivation

In general, bacteria are easily inactivated, while microorganisms likeGiardia intestinalis and Cryptosporidium among others, are verydifficult to inactivate. For example, the 1 log inactivation of GiardiaCysts at a temperature of 10° C. and at a pH of 7 requires a CT value of112. This means that the following disinfection alternatives can beused:

-   -   A concentration C of 1 ppm can be used for a time T of 112        minutes, achieving a CT of 112

${CT} = {{{1\mspace{11mu}\lbrack \frac{mg}{L} \rbrack} \times {112\mspace{11mu}\lbrack \min \rbrack}} = {112\mspace{11mu}\lbrack {\frac{mg}{L} \times \min} \rbrack}}$

-   -   A concentration C of 2 ppm can be used for a time T of 56        minutes, achieving a CT of 112

${CT} = {{{2\mspace{11mu}\lbrack \frac{mg}{L} \rbrack} \times {56\mspace{11mu}\lbrack \min \rbrack}} = {112\mspace{11mu}\lbrack {\frac{mg}{L} \times \min} \rbrack}}$

Thus, from the above example, it will be appreciated that to achieve thesame CT value, a higher concentration C results in a lower applicationtime T.

Proper disinfection must be achieved in recreational water bodies toprovide safe sanitary conditions for direct contact purposes. Eventhough some microorganisms are easily inactivated by conventional pooldisinfection levels, there are microorganisms that are resistant toconventional disinfection and filtration methods, and therefore requireother types of treatment for providing a sanitary-safe water body.

Therefore, there arises a need for a water treatment system and methodthat allows for minimizing the risk of contamination in large waterbodies from microorganisms that are commonly found in recreationalwaters, such as bacteria, protozoa, amoebas, microalgae and parasites,amongst others, by solving the inefficiencies current methods andsystems in an innovative manner and at low costs.

SUMMARY

The present invention provides a system and method for treating a largebody of water in order to make the water suitable for recreationalpurposes.

Methods and systems according to the principles of the invention providea low cost sanitary system and method that minimize the risks ofcontamination of microorganisms such as bacteria, protozoa, amoebas,microalgae and parasites, among others. Such system and method may beemployed in swimming lakes and man-made large water bodies, amongothers.

In either case, the principles of the invention include designating twodifferent treatment zones in the large body of water. The two zones havedifferent configurations and treatment methods. The first zone is asedimentation zone. This zone is used mainly to provide treatment andsettling of microorganisms and/or contaminants to inactivate and/orremove them from the water body. The second zone is a dissipation zone.This zone is where the main direct contact recreational water activitiesare intended to occur. In this dissipation zone, a water flow isestablished that along with the natural currents produced by windsand/or water temperature differences, allow generating a waterdissipation pattern of the volume of water within the dissipation zone 2into the sedimentation zone 1. In addition, continuous disinfection ofthe water volume in the dissipation zone is provided.

Therefore, according to a first aspect of the invention, there isprovided a low cost and sanitary efficient method for providing largewater bodies for direct contact recreational purposes, of at least 3,000m², the method comprising: designating a sedimentation zone 1 and adissipation zone 2 in the large water body, applying a disinfectionmethod based on a CT index and applying an efficient amount of aflocculant composition into the sedimentation zone 1 that aids in thesettling of different microorganisms and/or contaminants that arepresent in the sedimentation zone 1, and minimally disturb the watervolume within the sedimentation zone, whereby disturbance to thesedimentation process is minimized; maintaining a permanent chlorineresidual in the dissipation zone 2 water volume by adding an efficientamount of a chlorine disinfectant into the dissipation zone 2 so that atleast a 0.5 mg/L free chlorine level is maintained in the water volumecontained within the dissipation zone 2; injecting water to thedissipation zone by means of one or more inlet nozzles that along withthe natural currents produced by winds and/or water temperaturedifferences, allow generating a water dissipation pattern of the volumeof water within the dissipation zone 2 into the sedimentation zone 1,and wherein the dissipation zone 2 is configured and arranged to allow aContamination Reduction Index (CRI) of up to 30 minutes.

According to further aspects according to the method described in thepreceding paragraph, the sedimentation zone 1 and the dissipation zone 2are not separated by a physical barrier and the ratio between the watervolume within the dissipation zone and the water volume within thesedimentation zone is from 1:2 to 1:40. The method further comprisesdesigning the sedimentation zone so that, as a daily average, no morethan 20% of the total number of bathers utilizing the large water bodyare present in the sedimentation zone 1, and wherein the sedimentationzone 1 is intended mainly for secondary non-direct recreational contactpurposes; further comprising designing the dissipation zone for directcontact purposes such as swimming; and/or further comprising designingthe dissipation zone so that as a daily average, 80% or more of theswimmers utilizing the large water body are present in the dissipationzone 2.

It will be appreciated that the large water bodies with which theprinciples of the present invention may be utilized, include existingwater bodies (such as swimming lakes) or water bodies that areconstructed.

According to a second aspect of the invention, there is provided asystem for establishing a large water body suitable for direct contactrecreational purposes, the large water body of the type covering atleast 3,000 m², and having a periphery 12 and a bottom, comprising: asedimentation zone 1 located within a portion of the large water body 3and along a portion of the periphery 12; a system for dosing chemicals19 within the sedimentation zone arranged and configured to apply: i)disinfectant agents in the water volume within the sedimentation zone toachieve a CT index of at least 42 every 72 hours, where C is defined asthe concentration and T is defined as the minimum contact time, and ii)flocculant agents into the sedimentation zone that aid in the settlingprocess of the different microorganisms, parasites, and protozoa thatare present in the water body and inactivated by the CT cycle; adissipation zone located within a portion of the large water body andalong a portion of the periphery 12; a system for dosing chemicals 29into the dissipation zone configured to maintain a permanent chlorineresidual in the water volume within the dissipation zone water, whereinat least a 0.5 mg/L free chlorine level is maintained in the watervolume located within the dissipation zone; and one or more inletnozzles 26 throughout the dissipation zone 2 within the dissipation zonearranged and configured to inject water to the dissipation zone, whichalong with the natural currents produced by winds and/or watertemperature differences, allow generating a water dissipation pattern ofthe volume of water within the dissipation zone 2 into the sedimentationzone 1 and minimally disturb the water volume within the sedimentationzone, whereby disturbance to the sedimentation process is minimized.

The advantages and features which characterize the inventions arepointed out with particularity in the claims annexed hereto and forminga part hereof. For a better understanding of the inventions, however,reference should be had to the drawings which form a part hereof and tothe accompanying descriptive matter, in which there is illustrated anddescribed preferred embodiments of the inventions.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, wherein like numerals represent like partsthroughout the several views:

FIG. 1 illustrates one example embodiment of a large water bodycomprising two separate zones, a sedimentation zone 1 and a dissipationzone 2.

FIG. 2 illustrates one example embodiment of a large water bodyincluding a sedimentation zone 1 and two dissipation zones 2.

FIG. 3 illustrates shows an enlarged portion of the water body of FIG. 1showing an embodiment sedimentation zone 1 and dissipation zone 2.

FIGS. 4A-4G show an exemplary embodiment of the invention where themethod of the invention is illustrated.

FIG. 5 schematically illustrates a functional block diagram of thevarious components which may be utilized in an embodiment of theinvention.

FIG. 6 schematically illustrates a portion of the periphery 12 of alarge water body in an area of the dissipation zone 2.

FIG. 7 illustrates an embodiment method utilized in connection with thepresent invention.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying figures.While embodiments of the invention may be described, modifications,adaptions, and other implementations are possible. For example,substitutions, additions, or modifications may be made to the elementsillustrated in the drawings, and the methods described herein may bemodified by substituting, reordering, or adding stages to the disclosedmethods. Accordingly, the following detailed description does not limitthe scope of the invention.

The present invention relates to a low cost and sanitary efficientmethod for providing large water bodies with two different treatmentzones for direct contact recreational purposes.

The low cost and sanitary efficient method of the present inventionaddresses the technical inefficiencies of conventional swimming pooltechnologies in maintaining safe and sanitary conditions in water bodiesby combining the technical features of a dissipation zone 2 for directcontact recreational purposes, which has a particular and efficientwater dissipation pattern as well as a minimum permanent concentrationof a chlorine disinfectant, together with a sedimentation zone 1 that isintended mainly for secondary non-direct recreational contact purposes,which is not physically separated from the dissipation zone 2 and isconfigured to inactivate, flocculate and eliminate dangerousmicroorganisms previously dissipated from the dissipation zone 2.

As described herein, the combined disinfection methods, efficientdiffusion patterns and sedimentation capacity of the water bodiesaccording to the present invention create unprecedented saferenvironments for water recreational purposes that have not beendescribed nor applied before and that solve the inefficiencies ofconventional swimming pool technologies and those of partially treatedlarge water bodies, allowing thus the creation of recreational waterbodies that minimize the risk of infections caused by microorganisms(e.g., such as bacteria, protozoa, amoebas, microalgae and parasites,among others), thus solving the inefficiencies of current methods andsystems in an innovative manner and at low costs.

In the context of the present invention, direct contact recreationalactivities involve repeated or continuous direct contact of bathers withthe water, involving a significant risk of ingestion of water, such asswimming, water skiing, diving, surfing and wading by children. On theother hand, secondary contact or non-contact recreational uses do notinvolve the direct contact of bathers with water and therefore do notinvolve a significant risk of water ingestion, such as fishing, orboating activities.

The method of the present invention allows inactivating and/or removingcontaminants and/or microorganisms from large water bodies, where suchmicroorganisms can come from the air, water sources, externalcontamination, or more likely from bathers that access the water bodywho are carrying such contaminants.

More specifically, the present invention relates to a low cost andsanitary efficient method for providing large water bodies suitable fordirect contact recreational purposes, wherein the method is defined,inter alia, by:

-   -   designating a sedimentation zone 1 and a dissipation zone 2 in        the large water body, both having different configurations and        treatment methods, wherein        -   the sedimentation zone 1 and the dissipation zone 2 are            located within the same water body 3, and are not separated            by a physical barrier,        -   the sedimentation zone 1 can have a second purpose (e.g., in            addition to functioning as the sedimentation zone), that is            an aesthetic purpose and is intended mainly for secondary            non-direct recreational contact purposes, and is therefore            designed to have a density of bathers lower than the            dissipation zone 2,        -   the dissipation zone 2 is used for direct contact purposes,            such as swimming and bathing, and is designed to have a high            density of bathers,    -   applying a disinfection method based on a CT index into the        sedimentation zone 1 water volume,    -   applying an efficient amount of a flocculant composition into        the sedimentation zone 1 that aids in the settling of different        microorganisms and/or contaminants that are present in the        sedimentation zone 1, and wherein water flows and water        circulation within the sedimentation zone 1 are maintained to        allow proper sedimentation, preferably water flows and water        circulation within the sedimentation zone 1 are maintained at a        minimum, whereby disturbance to the sedimentation process is        minimized;    -   maintaining a permanent chlorine residual in the dissipation        zone 2 water volume, and    -   injecting water to the dissipation zone 2 by means of one or        more inlet nozzles that along with the natural currents produced        by winds and/or water temperature differences, allow generating        a water dissipation pattern of the volume of water within the        dissipation zone 2 into the sedimentation zone 1, and        wherein the dissipation zone 2 is configured to allow a        Contamination Reduction Index (CRI).

More specifically, the present invention also relates to a system forestablishing a large water body 3 suitable for direct contactrecreational purposes, wherein the system comprises:

-   -   a) a sedimentation zone 1 located within a portion of the large        water body 3 and along a portion of the periphery;    -   b) a system for dosing chemicals along the periphery within the        sedimentation zone 1 arranged and configured to apply:        -   i) disinfectant agents in the water volume within the            sedimentation zone 1 to achieve a CT index of at least 42            every 72 hours, where C is defined as the concentration and            T is defined as the minimum contact time; and        -   ii) a flocculant composition into the sedimentation zone 1            that aids in the settling process of the different            microorganisms, parasites, and protozoa that are present in            the water body and inactivated by the CT cycle;    -   c) a dissipation zone 2 located within a portion of the large        water body and along a portion of the periphery;    -   d) one or more inlet nozzles 26 along the periphery within the        dissipation zone 2 arranged and configured to inject water to        the dissipation zone 2 to generate a diffusion pattern of the        water volume within the dissipation zone,    -   e) a system for dosing chemicals 29 into the dissipation zone 2        configured to maintain a permanent chlorine residual in the        water volume within the dissipation zone water, wherein at least        a 0.5 mg/L free chlorine level is maintained in the water volume        located within the dissipation zone.

The large water bodies with which the principles of the presentinvention may be practiced, can be natural or artificial water bodiesand can have a surface area of at least 3,000 m², more preferably atleast 8,000 m² and even more preferably at least 12,000 m² and mostpreferably at least 24,000 m².

In reference to FIG. 1, two different zones are designated within thelarge water body 3, a first sedimentation zone 1 and a seconddissipation zone 2 both having different configurations, disinfectionmethods, cleaning requirements, and dissipation conditions.

Both zones are located within the same large water body 3, and are notseparated by a physical barrier, as the dissipation zone 2 is open intothe sedimentation zone 1. Both zones may be delimited by the use of adelimitation means or device 4. Therefore, in an embodiment of theinvention, a delimitation means 4 separates the sedimentation zone 1 andthe dissipation zone 2. The means of delimitation 4 according to theinvention may be selected from the group comprising a visualdelimitation, overhead flags, a series of buoys, a flotation line, adelimitation line, a slope change, different depths and combinationsthereof, among others. In other embodiments, the approximate location ofthe means of delimitation can be established by other means such as in abrochure, designations by signage or rules, a handbook, a user guidelineand by written and/or verbal instructions, among others.

According to the invention, the ratio between the volume containedwithin the dissipation zone 2 and the volume contained within thesedimentation zone 1 is preferably 1:2, more preferably 1:10, even morepreferably 1:30 and most preferably 1:40.

The sedimentation zone 1 is configured to provide treatment and settlingof contaminants and/or microorganisms such as bacteria, protozoa,amoebas, microalgae and parasites, amongst others in order to inactivateand remove them from the water body 3. The sedimentation zone 1 includesspecific features that allow an efficient sedimentation of the suspendedcontaminants and microorganisms and avoiding their resuspension,including: (a) it has a defined depth, (b) it is designed to have alimited density of bathers, (c) it includes a disinfection treatmentbased on a CT index, (d) it includes the application of flocculants toaid in the settling of microorganisms and/or contaminants, and (e) ithas a defined surface that ensures maintaining a calm water body tominimize water flows and water circulation that may interfere with thesettling process. The above features are described in detail below:

-   -   a) A defined depth: The sedimentation zone 1 is designed so that        its depth allows an efficient settling of the microorganisms. In        an embodiment of the invention, the depth of the sedimentation        zone 1 is at least 1.8 meters at its deepest point, which        contributes in preventing bathers from stepping over the bottom        surface of the sedimentation zone which might cause the        re-suspension of microorganisms and impurities that have already        settled on the bottom of the sedimentation zone 1. In other        embodiments of the invention, the depth of the sedimentation        zone 1 is at least 2 meters at its deepest point, and preferably        at least 2.2 meters at its deepest point.    -   b) A limited density of bathers: The sedimentation zone is        intended mainly for secondary non-direct recreational contact        purposes; and due to its depth, potential bathers that want to        access and stay in such zone would tend to go back to the        dissipation zone 2 which is suitable for direct contact        recreational purposes, and therefore the sedimentation zone 1 is        designed so the that density of bathers in such sedimentation        zone is limited to less than 20% of the total bathers present in        the large water body 3 and more preferably less than 10% of the        total bathers present in the large water body 3. Such 20% and        10% of the total bathers are calculated as a daily average,        taking in account the total number of bathers that enter the        water body 3.    -   c) A disinfection treatment based on a CT index: The        sedimentation zone 1 is treated based on a CT index, wherein the        CT can be determined to be the one suitable to inactivate most        dangerous microorganisms such as Naegleria Fowleri, Giardia or        Cryptosporidium, among others. The disinfection treatment based        on a CT index requires that the sedimentation zone 1 is treated        by adding disinfectant agents to achieve a specific        concentration “C” during a minimum contact time of “T” in the        complete water volume of the sedimentation zone 1. In a        preferred realization of the invention, a disinfection method is        performed such that disinfectant agents are applied to the water        volume contained in the sedimentation zone 1 to achieve a CT        index of at least 42 every 72 hours, since the same has proven        to be a CT index that provides safe and sanitary conditions in        order to inactivate not only Naegleria Fowleri but other        dangerous microorganisms that are present in recreational water        bodies.    -   It is important to emphasize that some microorganisms, such as        the Naegleria Fowleri, do not survive in seawater or salty        water. Nonetheless, if the water body 3 according to the present        invention contains seawater, salty water or a combination        thereof, the sedimentation zone 1 is in any case configured so        that disinfectant agents are applied to achieve a CT index of at        least 42 every 72 hours. In other embodiments of the invention,        disinfectants agents are applied to achieve a CT index according        to any of those indexes listed in Table 1, or other defined        accordingly, in a timeframe of at least 24 hours, preferably at        least 48 hours and even more preferably of up 72 hours.    -   d) Application of flocculants: The sedimentation zone 1 is        treated with a flocculant composition that aids in the settling        process of contaminants and/or microorganisms that are present        in the water body and that may have been inactivated through the        CT cycles.    -   In an embodiment of the invention, the flocculant composition        comprises one or more flocculant agents selected from the group        comprising organic and inorganic flocculants. Preferably, the        flocculant agents are selected from inorganic flocculants        comprising synthetic polymers, quaternary ammonium cationic        polymers, polycationic polymers, aluminum salts, calcium oxide,        calcium hydroxide and mixtures thereof.    -   In an embodiment of the invention, the flocculant agents are        preferably selected from the group comprising a cationic or        anionic polymeric flocculant and are preferably added to the        sedimentation zone 1 at least once every 7 days at a rate of        0.03 g to 3.0 g per m³ of water volume of the sedimentation zone        1.    -   e) A large surface: The sedimentation zone 1 has a large surface        of at least 1,500 m², preferably at least 6,000 m² and even more        preferably of at least 10,000 m², which allows minimizing the        effect of water flows and water circulation that can affect the        resuspension of settled contaminants from the bottom surface of        the sedimentation zone 1.

The dissipation zone 2 according to the present invention is suitablefor direct contact recreational purposes and is preferably locatednearby the periphery 12 of the water body 3 and is open to thesedimentation zone 1. The dissipation zone 2 is the zone that isdesignated to have a high density of bathers. The dissipation zone 2 hasspecific characteristics and conditions to provide a continuousdisinfection to the water volume within the dissipation zone 2 and toallow an efficient dissipation of the water into the sedimentation zone1. The dissipation zone is therefore defined by the following three maintechnical features:

-   -   a) A continuous disinfection: A permanent chlorine residual is        maintained in the dissipation zone 2, where such zone is        disinfected so that at least a 0.5 mg/L free chlorine level is        maintained in the water volume contained within the dissipation        zone. According to the main embodiment of the invention,        chlorine is the preferred disinfectant agent to be applied into        the dissipation zone, however, other type of disinfectants that        achieve suitable disinfection parameters can also be used, such        as bromine, ozone, its derivatives and mixtures thereof.    -   b) A specific depth and geometry: The dissipation zone 2 is        designed so that it has a design and depth that is suitable for        bathers accessing and entering the dissipation zone. In an        embodiment of the invention, the dissipation zone has a downward        slope and a depth of 1.4 meters at its deepest point.        Preferably, the dissipation zone comprises a downward slope from        the periphery 12 to the bottom surface at an angle a that        results in a slope of up to 15% to achieve a safe entry to the        large water body, and so that it is suitable for bathers to stay        in such area. In an alternative embodiment, the dissipation zone        2 is designed so that it has a depth of 1.6 meters at its        deepest point, and more preferably 1.8 meters at its deepest        point.    -   c) One or more inlet nozzles: The dissipation zone 2 comprises        one or more inlet nozzles 26 located within such zone in order        to provide a water flow into the dissipation zone 2, that along        with the natural influence of water currents produced by winds        and/or the horizontal and vertical water temperature differences        in the water body, will cause water movement and renewal of such        water volume contained in the dissipation zone 2 that is open to        the sedimentation zone 1. In an embodiment of the invention, the        location, design and configuration of the one or more inlet        nozzles 26 can vary to achieve different types of water renewal        patterns within the dissipation zone. The one or more inlet        nozzles 26 can be located along any section of the dissipation        zone, such as its periphery and/or center. In a particular        embodiment, the one or more inlet nozzles 26 can be configured        to add an efficient amount of a chlorine disinfectant into the        dissipation zone in order to maintain a free chlorine        concentration of at least 0.5 mg/L free chlorine level is        described in (a).

The dissipation zone 2 is the zone that is designated to have a highdensity of bathers, where at least 80% and more preferably at least 90%of the total number of bathers within the large water body 3 is presentin the dissipation zone 2 with a maximum density of 1 bather per 2 m2,preferably a maximum density of 1 bather per 4 m², more preferably amaximum density of 1 bather per 6 m² and most preferably a maximumdensity of 1 bather per 8 m². Such 80% and 90% are calculated as a dailyaverage, taking in account the total number of bathers that enter thewater body 3, and where at least 80% and more preferably 90% of suchbathers are located in the dissipation zone 2.

The combination of the above zone elements relating to depth, geometryand one or more inlet nozzles 26 together with the natural influence ofwater currents produced by winds and/or the horizontal and verticalwater temperature differences in the water body, will cause watermovement and the dissipation of water volume contained in thedissipation zone 2 into the sedimentation zone 1, in addition to providea continuous disinfection within said dissipation zone 2 as described in(a).

It has been surprisingly found that the low cost and sanitary efficientmethod of the present invention addresses the technical inefficienciesof conventional swimming pool technologies in maintaining safe andsanitary conditions in large water bodies by combining the technicalfeatures of a dissipation zone 2 for direct contact recreationalpurposes, having a particular and efficient water dissipation pattern aswell as a minimum permanent amount of a disinfectant, which in the eventof a contamination event can safely and timely inactivate and dissipatedangerous microorganisms to a sedimentation zone 1 that is intendedmainly for secondary non-direct recreational contact purposes, whereinsaid sedimentation zone 1 is not physically separated from thedissipation zone 2 and which is configured to inactivate microorganismsby means of a CT disinfection method, as well as to flocculate andeliminate them in an efficient, safe manner at low costs.

There are currently no methods or systems that can address the technicalinefficiencies of conventional swimming pools in an efficient and lowcost way for large water bodies as the ones of the present invention,which combine the effects of an efficient water dissipation pattern andminimum disinfection standard in the zone that is aimed for directcontact recreational purposes, with a sedimentation zone 1 that isconfigured to inactivate, flocculate and eliminate contaminants and/ordangerous microorganisms previously dissipated from a dissipation zone.Even though some larger water bodies, such as natural swimming lakes areable to somewhat recreate a dissipation pattern, they lack the technicalfeatures of the present invention, namely: a dissipation zone 2 having apermanent minimum concentration of a disinfectant and a particular andefficient dissipation pattern as well as a sedimentation zone 1 thatcombines the application of a CT disinfection method with theapplication of flocculant agents that allow a proper inactivation andelimination of contaminants and/or microorganisms to maintain a sanitaryand safe zone for recreational water purposes.

Therefore, the combined disinfection methods, efficient diffusionpattern and sedimentation capacity of the water bodies according to thepresent invention create unprecedented safe environments for waterrecreational purposes that have not been described nor applied beforeand that solve the inefficiencies of conventional swimming pooltechnologies and those of partly treated large water bodies, allowingthus the creation of recreational water bodies that minimize the risk ofinfections caused by microorganisms such as bacteria, protozoa, amoebas,microalgae and parasites, amongst others, solving thus theinefficiencies of current methods and systems in an innovative mannerand at low costs.

As previously mentioned, the dissipation zone 2 is configured to createan efficient diffusion pattern of the volume within the dissipation zone2 due to the combined effect of the one or more inlet nozzles 26 thatinject a water flow into such zone along with the natural influence ofwater currents produced by winds and/or the horizontal and verticalwater temperature differences of the water body, which creates a waterflow and efficient diffusion pattern within the dissipation zone 2 thatforces such water volume to leave the dissipation zone 2 and cross overto the sedimentation zone 1. The circulation created by the one or moreinlet nozzles 26 and the natural influence of water currents produced bywinds and/or the horizontal and vertical water temperature differencesin the water body, contribute to generate a dissipation rate in suchdissipation zone 2, as the water flows that enter such zone push thewater volume into leaving the dissipation zone 2 and reaching thesedimentation zone 1. Therefore, there is a dissipation pattern thatallows renewing the water volume contained within the dissipation zone 2based on the configuration and capacity of the one or more inlet nozzles26, on the natural influence of water currents produced by winds and/orthe horizontal and vertical water temperature distribution in the waterbody, as well as on the presence of an open hydraulic connection to thesedimentation zone.

In certain embodiments of the invention, the water body may be subjectto stronger winds that can influence the dissipation pattern within thedissipation zone. In such a case, the circulation created by the one ormore inlet nozzles within the dissipation zone can be adjusted asnecessary to maintain a suitable dissipation pattern. For instance,where winds positively influence the dissipation pattern within thedissipation zone, the water flow from the one or more inlet nozzles canbe minimized or suppressed entirely if the dissipation pattern createdby the winds is sufficient to generate the necessary dissipation ofwater volume from the dissipation zone to the sedimentation zone. On theother hand, where winds adversely influence the dissipation patternwithin the dissipation zone, the water flow from the one or more inletnozzles can be adjusted to generate the necessary dissipation of watervolume from the dissipation zone to the sedimentation zone

This is a clear advantage compared to conventional swimming pools, asswimming pools do not have a separate dissipation zone 2 in order tocreate a dissipation pattern, and therefore in the method of the presentinvention by combining a permanent residual disinfectant concentrationand an efficient dissipation pattern in the dissipation zone 2, suchzone allows to withstand a massive use of bathers without compromisingthe sanitary quality of such zone due to the fact that in the event of acontamination, the microorganisms can be dissipated in a more efficientand safe way compared to conventional swimming pool.

By having an efficient dissipation pattern, when a contamination eventtakes place, for example, contamination brought in by new bathers withinfectious microorganisms or by other means, said contamination can bedissipated from the dissipation zone 2 into the sedimentation zone 1 forits inactivation and/or removal. In the context of the invention, acontamination event is referred to as any event where organic orinorganic substances that pose a risk to the health of the bathers ormicroorganisms are brought to the water body.

The efficient dissipation pattern of the present invention is differentthan conventional swimming pools, where any contamination brought in bynew infected bathers or by an infection event may remain in the sameconfined water volume for hours or even longer before it is removed orproperly inactivated, causing a potential risk for other bathers. Aspreviously mentioned, certain microorganisms are highly resistant toconventional filtration and disinfection methods of swimming pools, andtherefore can survive many hours or even days within the pool watervolume before they are removed.

It is important to mention that although the method and system of thepresent invention do not require filtering the complete water volume atconventional swimming pool rates (i.e. from one to six times per day),the use of conventional filtration systems may be used as an additionaltreatment to the water body. Such use may be due to local regulatoryrequirements, or decisions by the owner/developer. The use of aconventional filtration system of the water body is compatible with themethod and system of the present invention, however, water flows in thesedimentation zone should allow for proper sedimentation of particles.Such use of a conventional filtration system as an additional treatmentto the water body, however, may involve higher construction andoperation costs and therefore may be implemented in water bodies havinga volume of preferably up to 50.000 m3.

In addition, although it is not required to maintain a permanent freechlorine level in the sedimentation zone, such levels may be required bylocal regulations or by owner's decisions, which are not incompatiblewith the method and system from the present invention.

The permanent chlorine level in the dissipation zone 2 can be achievedby the use of chlorine tablets, by applying diluted chlorine through theone or more inlet nozzles 26 located in the dissipation zone 2, or bymanually adding chlorine to such zone in an effective amount to maintainat least a 0.5 mg/L free chlorine level.

In an embodiment of the invention, the water injected to the dissipationzone 2 through the one or more inlet nozzles 26 is treated withultraviolet light (UV).

In an embodiment of the invention, the water body comprises a pluralityof separate dissipation zones 2, preferably located along the periphery12 of the water body 3 and open to the sedimentation zone 1, wherein thedissipation zones 2 are used for swimming, bathing, and other directcontact recreational purposes, whereas the sedimentation zone 1 has anaesthetic purpose and is intended mainly for secondary non-directrecreational contact purposes.

For the sedimentation zone 1, a daily cleaning of the bottom surface toremove settled particles and fallen debris is not essential, since suchzone may have a more natural aspect such as natural lakes and lagoonswhere the bottom surface can have a darker tonality than the bottom inthe dissipation zone 2. In a preferred embodiment of the invention, thebottom surface of the sedimentation zone 1 is cleaned at least onceevery 7-days period. However, other time periods may be employed. In anembodiment of the invention, a bottom surface cleaning device isprovided to clean a bottom surface.

The dissipation zone 2 requires a periodic cleaning of the bottomsurface in order to maintain the bottom surface of such zones free ofparticles that may generate an aesthetic, safety, or sanitary impact inthe water. Also, such zone must be periodically cleaned in order toprevent any resuspension of settled microorganisms. In a preferredembodiment of the invention, the bottom surface of the dissipation zone2 is cleaned at least once per every 72-hours period. However, othertime periods may be employed.

In an embodiment of the invention, the sedimentation zone 1 is limitedto an even lower density of bathers of less than 10% of the totalbathers present in the large water body 3. In other preferredembodiments, the sedimentation zone 1 does not allow the presence ofbathers for direct contact recreational purposes and is configured toallow only the practice of aquatic sports with secondary contactpurposes.

The ratio between the volume contained within the dissipation zone 2 andthe volume contained within the sedimentation zone 1 is preferably 1:2,more preferably 1:10, even more preferably 1:30 and most preferably1:40, wherein such relation is calculated as the sum of all watervolumes contained within the dissipation zones 2, divided by thesedimentation zone 1 water volume.

In an embodiment of the invention, the water from the sedimentation zone1 and that has already been treated, can be extracted from thesedimentation zone 1 and sent to the dissipation zone 2. Such water canbe partially or completely mixed with make-up water.

In addition to minimizing the risk of growth of microorganisms, thepresent invention also eliminates particles and contaminants that are besusceptible to flocculation. In an embodiment of the invention, theflocculant agents can be selected from the group comprising organic andinorganic flocculants. Preferably, the flocculant agents are selectedfrom inorganic flocculants comprising synthetic polymers, quaternaryammonium cationic polymers, polycationic polymers, aluminum salts,calcium oxide, calcium hydroxide and mixtures thereof. Preferably, theflocculants added to the sedimentation zone 1 are selected from thegroup comprising a cationic or anionic polymeric flocculant and mixturesthereof and are preferably added to the sedimentation zone 1 at leastonce every 7 days at a rate of 0.03 g to 3.0 g per m3 of water volume ofthe sedimentation zone 1.

Turning now to FIG. 5, a functional block diagram illustrating thevarious components which may be utilized in connection with anembodiment of the present invention is shown. The large water body isshown at designation 3. It will be appreciated that while the shape ofthe water body in FIG. 5 is shown with four-sided shape, the shape isfor illustration only. Other embodiment shapes are illustrated in FIGS.1-3. The sedimentation zone 1 and dissipation zone 2 are shown asdesignated portions of the large water body 3. The boundary for thedelimitation means 4, which is not a physical barrier, is shown at themeeting point or intersection of the sedimentation zone 1 anddissipation zone 2. The periphery 12 extends about the edge of the largewater body 3.

Input water to pump 25 is provided from the dissipation zone 2, treatedwater from the sedimentation zone 1, and any required or desired make-upwater from block 27. The amount of water from the various locations maybe adjusted based on establishing the appropriate current/flow withinthe large water body 3, and evaporation, among other factors. The pump25 provides water to the one or more inlet nozzles 26, which togetherwith the natural influence of water currents produced by winds and/orthe horizontal and vertical water temperature differences of the waterbody, establish the current or flow (indicated by the plurality ofarrows 14) from the dissipation zone 2 to the sedimentation zone 1. Thesystem for dosing chemicals 29 provides chemicals to the pump 25 andoptionally provides chemicals directly to the dissipation zone 2.

The system for dosing chemicals 19 comprising one or more inlet nozzlesprovides the necessary chemicals to the sedimentation zone 1. Forexample, the system for dosing chemicals 19 provides the necessarydisinfectant for the desired CT cycle and the flocculant composition.The system for dosing chemicals 19 comprising one or more inlet nozzlesmay be extended for additional lengths or positions along the periphery12 for treatment based on the size of the large water body 3. Treatedwater can also be drawn from the sedimentation zone 1 through a pump 30to the pump 25 or to the system for dosing chemicals 19.

Now referring to FIG. 6, a schematic cross section of a portion of thedissipation zone 2 is illustrated. The periphery 12 is shown as thedemarcation between the shore or edge 15 and the water within the largewater body 3. The downward slope from the periphery 12 to the bottomsurface is preferably at an angle a that results in a slope of up to15%. This provides an entrance into the water 16 from the shore 15 thatis safe and generally comfortable for bathers entering the water.

The Contamination Reduction Index (CRI) is an index calculated based ona standardized protocol developed in the present disclosure to representthe safety and sanitary conditions of a water body treated according tothe method of the invention.

In the context of the invention, the Contamination Reduction Index (CRI)is an Index that determines the time in minutes needed to dissipate asample of an aqueous solution out of a defined water zone. Inparticular, the Contamination Reduction Index (CRI) indicates the timein minutes counted as from the moment that a sample of a tinted solutionis added to a particular point within a dissipation zone 2 until thetinted solution is dissipated and is not visually detectable in saiddissipation zone 2.

The Contamination Reduction Index (CRI) fairly represents the time thatit will require for an aqueous contaminant brought in by a bather or byother means into a dissipation zone 2 to be dissipated out of thatdissipation zone 2 into the sedimentation zone 1. The CRI is therefore asuitable and objective standard to assess the ability of said water zoneto dissipate a contaminant in a short timeframe into the sedimentationzone 1, wherein said contaminant can be subsequently inactivated,flocculated and removed out of the sedimentation zone 1, maintainingthus safe and sanitary conditions in case of a contamination event.

The CRI, which counts the time as from the moment that the sample of aspecific tinted solution is added into the dissipation zone 2 until thesame is not visually detectable in said dissipation zone 2, depends onseveral of factors. In the context of the present invention, the CRI ofthe dissipation zone 2 is influenced mainly by: the presence of an openconnection to a sedimentation zone 1, the disposition of one or moreinlet nozzles that inject a water flow into the dissipation zone 2 andthe natural influence of water currents produced by winds and/or thehorizontal and vertical water temperature differences of the water body.

In a preferred embodiment of the invention, the dissipation zone 2 isconfigured to allow a Contamination Reduction Index (CRI) of up to 30minutes, more preferably of up to 25 minutes, more preferably of up to20 minutes and even more preferably of up to 15 minutes and even morepreferably of up to 10 minutes.

The CRI can be determined in several ways, either from qualitativeand/or quantitative data and analysis.

In one embodiment, the information regarding the time required tocomplete the dissipation of a sample of a tinted solution can beobtained qualitatively by visual inspection, methods based onexperience, or estimate projections. In other embodiment, theinformation regarding the time required to complete the dissipation of asample of a tinted solution can be obtained from one or more manual orautomatic monitoring devices.

The standardized protocol to determine the Contamination Reduction Index(CRI) according to the present invention comprises assessing the timerequired for a water zone (a dissipation zone 2) of 144 m3 to dissipate7L of a tinted aqueous solution comprising 30 g/L of carmine (naturalred 4) and 77 g/L of NaCl out of said water zone until the tintedsolution is not visually detectable in said water zone. While the testis being conducted, and in order to ensure the visual detection of thetinted solution in the dissipation zone 2, the water zone should be freeof chemical agents that may reduce the detection of colorant, such aschlorine and other disinfectant agents. Once the test is finalized,chemical agents should be reestablished according to the specificationsof the dissipation zone 2.

The Contamination Reduction Index (CRI) provides therefore an objectiveprojection of the efficient water dissipation patterns of thedissipation zone 2 according to the present invention, which combinedwith a permanent minimum disinfectant concentration as well as with anopen connection to a sedimentation zone 1 that is configured toinactivate, flocculate and eliminate dangerous microorganisms, amongstother factors, allows providing safe and sanitary conditions for largewater bodies for direct contact recreational purposes.

The combined disinfection methods, efficient diffusion pattern andsedimentation capacity of the water bodies according to the presentinvention create unprecedented safe environments for water recreationalpurposes that have not been described nor applied before and that solvethe inefficiencies of conventional swimming pool technologies and thoseof partly treated large water bodies, allowing thus the creation ofrecreational water bodies that minimize the risk of infections caused bymicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites, amongst others, solving thus the inefficiencies of currentmethods and systems in an innovative manner and at low costs.

In addition to the above, the method of the present invention alsoallows to reduce costs compared to conventional swimming pools systemsand methods, where for example a 2 hectare conventional swimming poolwould require a yearly operation cost of up to US$ 1.9MM consideringchemical use and electricity use, whereas the method of the presentinvention would bring a yearly operation cost to less than US$ 140,000(considering chemicals and energy costs as well) up to a 90% ofreduction in annual maintenance costs.

Additionally, the method of the present invention allows minimizing therisk of contamination from microorganisms that current technologies arenot capable of treating. As previously mentioned, current swimming pooltechnologies or partial treatment technologies for man-made water bodieshave not been able to efficiently provide a high sanitary effect andhave not been able to inactivate and/or remove microorganisms that causerecreational water illnesses or other infections that could even lead tofatal outcomes. On the other hand, the method from the presentinvention, in addition to having low capital and operation costs, allowsinactivating and/or removing microorganisms from recreational waterbodies in an innovative manner, generating a new concept of watersanitation at low costs.

By using the method of the present invention, optimum settling andsanitary conditions are achieved, where the sedimentation zone 1 isdesigned to efficiently settle the microorganisms contained within suchsedimentation zone 1 water volume, and where the dissipation zone 2allows maintaining safe and sanitary conditions for high density ofbathers at low costs.

Referring to FIG. 7, there is provided an overview of the stepsdesignated at 700 in an embodiment in accordance with the principles ofthe invention. In addition, the steps illustrated in FIG. 7 do notrequire that the steps be performed in the order shown.

First at step 701, a sedimentation zone 1 and dissipation zone 2 aredesignated within the same large water body 3. The two zones are notseparated by a physical barrier and the ratio between the volume ofwater contained within the dissipation zone 2 and the volume containedwithin the sedimentation zone 1 is from 1:2 to 1:40. In addition tofunctioning for disinfection and sedimentation, the sedimentation zone 1also has an aesthetic purpose and is used mainly for the practice ofaquatic sports with secondary contact purposes. It is therefore designedto have a density of bathers lower than the dissipation zone 2, whereinas a daily average no more than 20% of the total number of batherswithin the large water body 3 is present in the sedimentation zone 1.The dissipation zone 2 is used for direct contact purposes, such asswimming and bathing. It is designed to have a high density of bathers,wherein as a daily average, at least 80% of the total number of batherswithin the large water body 3 is present in the dissipation zone 2 witha maximum density of 1 bather per 2 m2.

Next at block 702, a disinfection method based on a CT index is appliedto the sedimentation zone 1 water volume. The CT index requires that thesedimentation zone 1 is treated by adding disinfectant agents to achievea specific concentration “C” of the disinfectant during a minimumcontact time of “T” in the complete water volume of the sedimentationzone 1. The disinfection method is performed such that the disinfectantagents are applied to the water volume contained in the sedimentationzone 1 to achieve a CT index of at least 42 every 72 hours.

At block 703, an efficient amount of a flocculant composition is appliedinto the sedimentation zone 1. The flocculant aids in the settling ofdifferent microorganisms and/or contaminants that are present in thesedimentation zone 1. The water flows and water circulation within thesedimentation zone 1 are preferably maintained at a to allow a propersedimentation.

At block 704, a permanent chlorine residual is maintained in thedissipation zone 2 water volume by adding an efficient amount ofchlorine so that a level of at least a 0.5 mg/L free chlorine level ismaintained in the water volume contained within the dissipation zone 2.

At block 705, water is injected to the dissipation zone by means of oneor more inlet nozzles that—along with the natural currents produced bywinds and/or water temperature differences—allow generating a waterdissipation pattern of the volume of water within the dissipation zone 2into the sedimentation zone 1. The dissipation zone 2 is configured toallow a Contamination Reduction Index (CRI) of up to 30 minutes.

EXAMPLE I

In order to demonstrate the technical effect of the present invention,the following tests were conducted:

FIG. 3 shows a water body 3 having a sedimentation zone 1 and adissipation zone 2 according to the present invention, wherein thedissipation zone 2 comprises a nozzle system and has a residual chlorineconcentration of approximately 0.5 mg/L. FIG. 2 shows the estimatedlocation of the delimitation means 4, depicted as a dotted line, whichis not a physical barrier and also depicts an adjacent (but completelyindependent) swimming pool (7) having conventional swimming pooltechnology, i.e., not having separate dissipation 2 and sedimentation 1zones according to the present invention.

FIG. 4A shows that at t=0, 7 L of a red-tinted solution (5) comprising30 g/L a colorant natural red 4 and 77 g/L NaCl were directly added intoa spot located in the dissipation zone 2 of the water body 3 in order todetermine the CRI of said zone and to emulate, for example, the behaviorof an aqueous fecal contamination or other type of contamination broughtinto the dissipation zone 2, which is the zone that is mainly used forswimming, bathing, and direct contact recreational purposes. FIG. 4Aalso shows that an equivalent amount of a second red-tinted solution (6)was added into a spot inside the adjacent swimming pool (7).

At t=0, the water nozzles of the dissipation zone 2 were activated whilethe standard recirculation systems of the swimming pool (7) wereoperated according to its standard operating parameters.

At t=5 minutes (FIG. 4B), it is seen that the red-tinted solutionrapidly dissipates into the sedimentation zone 1 while in the swimmingpool (7) the presence of the red-tinted solution does not appear to havelowered since t=0.

At=10 minutes and at t=16 minutes (FIGS. 4C and 4D, respectively) therewas significantly less visible presence of the red-tinted solution (5)in the dissipation zone 2 whereas the swimming pool (7) still showed asubstantial amount of the red-tinted solution (6).

At t=20 minutes and at t=25 minutes (FIGS. 4E and 4F, respectively), thered-tinted solution (6) was still visibly present in the swimming pool(7) whereas no presence of the red-tinted solution (6) was visiblydetected in the dissipation zone 2. FIG. 3G shows that at t=60, thered-tinted solution (6) is visibly present in the swimming pool (7).

Upon finalization of the test, it was determined that the sedimentationzone 2 of the example had a CRI of 20 minutes whereas the swimming pool(7) had a CRI of 100 minutes, both indexes representing the time inminutes until no presence of the red-tinted solution was visuallydetected.

The foregoing allows predicting that in the event of a contaminationevent (for example, an aqueous fecal contamination or other type ofcontamination) occurring in a water body according to the presentinvention, the dissipation zone 2, along with the natural influence ofwater currents produced by winds and/or the temperature differences inthe water body, is able to safely and efficiently dissipate saidcontamination that might comprise dangerous microorganisms into asedimentation zone 1 for its subsequent inactivation, flocculation andremoval in a short time frame, thus minimizing the risk of bathersbecoming infected by dangerous microorganisms. Furthermore, since thedissipation zone 2 is configured to have a residual free chlorineconcentration of at least 0.5 mg/L, said dissipation zone 2 canwithstand a massive use of bathers without compromising the sanitaryquality of such zone due to the fact that in the event of acontamination, the microorganisms can be dissipated in a more efficientand safe way compared to conventional swimming pools maintaining at thesame time safe and sanitary conditions in the dissipation zone 2 whichis the zone that is used for direct contact recreational purposes. Underthe same scenario, when a fecal contamination or traces thereof carryingdangerous microorganisms takes place in a conventional swimming pool(7), the contamination would remain for an extended period in the watervolume, increasing the risk of bathers becoming infected by saiddangerous microorganisms.

Therefore, it has been shown that the combined disinfection methods,efficient diffusion pattern and sedimentation capacity of the waterbodies according to the present invention create unprecedented and saferenvironments for water recreational purposes compared to swimming pooltechnologies, allowing thus the creation of recreational water bodiesthat minimize the risk of infections caused by microorganisms such asbacteria, protozoa, amoebas, microalgae and parasites, amongst others,solving thus the inefficiencies of current methods and systems in aninnovative manner and at low costs.

EXAMPLE II

An artificial lake built in Florida, United States, having a totalsurface of about 7 acres (2.8 Hectares) became heavily contaminatedduring the process of being filled in with water due to the presence ofa nearby sand pile containing organic matter that was blown into thelake. Upon conducting laboratory tests, dangerous microorganisms,particularly Crystosporidium oocysts were identified in the water, whichremained present in the water even after several weeks that thecontamination took place.

The method according to the present invention was applied to theartificial lake.

The artificial lake was designated to include two different zones: onezone for direct contact recreational purposes designated as thedissipation zone 2 and a second zone for secondary contact recreationalpurposes, namely, such as for aesthetic purposes and for the practice ofwatersports designated as the sedimentation zone 1. The volume ratebetween the dissipation zone and the sedimentation zone was designed tobe approximately 1:6 and the sedimentation zone 1 comprised a depth of 2meters at its deepest point, which allowed an efficient settling of themicroorganisms.

The following parameters were applied to the artificial lake:

-   -   Sodium hypochlorite was added into the dissipation zone 2 so as        to achieve a permanent chlorine residual concentration of at        least a 0.5 mg/L of free chlorine.    -   Nozzles located at the periphery 12 of the dissipation zone        having an average water flow of 30 m3/hour were activated.    -   A disinfection treatment based on CT was applied adding chlorine        to the sedimentation zone 1 so as to achieve a CT index of 42        during a 72-hours interval in the sedimentation zone 1.    -   A composition comprising a cationic polymer flocculant was added        into the sedimentation zone 1 so that 1.5 g/m3 of water volume        were incorporated within a 7-days period.    -   Water flows were maintained at minimum in the sedimentation zone        1 whereby disturbance to the sedimentation process is minimized.

Upon application of the method of the present invention, laboratorytests were conducted and no Crystosporidium oocysts were identified,result that was confirmed in two subsequent tests as summarized in thefollowing Table 2.

TABLE 2 Sample Crystoporodium Location Appearance Odor pH OocystsSedimentation Clear No 8.28 Undetected Zone 1 Dissipation Clear No 8.30Undetected Zone 2 Dosing Line

In addition, as it is shown in the following Table 3, all water samplescomplied even with stricter physicochemical and microbiological waterquality standards such as the Chilean Norm NCh 409/1 2005 (DrinkingWater) for water requirements.

TABLE 3 Sample Sample Location Location Dissipation Norm NCh 409/1 2006Sedimentation Zone 2 Dosing Test Standard Zone 1 Line Turbidity <20 0.80.5 (NTU) True Color <20 <5 <5 (Pt—Co) Total Coliform Exempt <2 <2Bacteria NMP/100 mL Escherichia Exempt <2 <2 Coli NMP/100 mL * <2 =undetectable

This example confirms that the method according to the present inventionprovides a low cost and sanitary efficient method for providing largewater bodies with two different treatment zones for direct contactrecreational purposes, which allows minimizing the risk of growth ofmicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites, amongst others, solving thus the inefficiencies of currentmethods and systems in an innovative manner and at low costs.

The combined disinfection methods, efficient diffusion pattern andsedimentation capacity of the water bodies according to the presentinvention create unprecedented safe environments for water recreationalpurposes that have not been described nor applied before and that solvethe inefficiencies of conventional swimming pool technologies and thoseof partly treated large water bodies, allowing thus the creation ofrecreational water bodies that minimize the risk of infections caused bymicroorganisms such as bacteria, protozoa, amoebas, microalgae andparasites, amongst others, solving thus the inefficiencies of currentmethods and systems in an innovative manner and at low costs.

While certain embodiments of the invention have been described, otherembodiments may exist. Further, any disclosed method steps or stages maybe modified in any manner, including by reordering steps and/orinserting or deleting steps, without departing from the invention. Whilethe specification includes a detailed description and associateddrawings, the invention's scope is indicated by the following claims.Furthermore, while the specification has been described in languagespecific to structural features and/or methodological acts, the claimsare not limited to the features or acts described above. Rather, thespecific features and acts described above are disclosed as illustrativeaspects and embodiments of the invention. Various other aspects,embodiments, modifications, and equivalents thereof which, after readingthe description herein, may suggest themselves to one of ordinary skillin the art without departing from the spirit of the present invention orthe scope of the claimed subject matter.

What is claimed is:
 1. Low cost and sanitary efficient method forproviding a large water body suitable for direct contact recreationalpurposes, the large water body water having a surface of at least 3,000m², the method comprising: designating a sedimentation zone 1 and adissipation zone 2 in the large water body, both having differentconfigurations and treatment methods, wherein: the sedimentation zone 1and the dissipation zone 2 are located within the same water body 3, andare not separated by a physical barrier, wherein a ratio between avolume of water contained within the dissipation zone 2 and a volume ofwater contained within the sedimentation zone 1 is from 1:2 to 1:40; thesedimentation zone 1 has an aesthetic purpose and is used mainly forsecondary non-direct recreational contact purposes, wherein thesedimentation zone 1 is designed to have a density of bathers lower thanthe dissipation zone 2, wherein as a daily average no more than 20% ofthe total number of bathers within the large water body 3 are present inthe sedimentation zone 1; the dissipation zone 2 is used for directcontact purposes, such as swimming and bathing, and is designed to havea high density of bathers, wherein as a daily average, at least 80% ofthe total number of bathers within the large water body 3 are present inthe dissipation zone 2 with a maximum density of one bather per twosquare meters; applying a disinfection method based on a CT index intothe volume of water contained within the sedimentation zone 1, whereinthe CT index requires that the sedimentation zone 1 is treated by addingdisinfectant agents to achieve a specific concentration “C” of thedisinfectant agents during a minimum contact time of “T” in the volumeof water contained within the sedimentation zone 1, and wherein thedisinfection method is performed such that the disinfectant agents areapplied to the volume of water contained in the sedimentation zone 1 sothat the CT index is at least 42 every 72 hours; applying an efficientamount of a flocculant composition into the sedimentation zone 1 thataids in the settling of different microorganisms and/or contaminantsthat are present in the sedimentation zone 1, and wherein water flowsand water circulation within the sedimentation zone 1 are maintained toallow sedimentation; maintaining a permanent chlorine residual in thevolume of water contained in dissipation zone 2 by adding an efficientamount of chlorine so that at least a 0.5 mg/L free chlorine level ismaintained in the water volume contained within the dissipation zone 2;injecting water to the dissipation zone 2 by means of one or more inletnozzles 26 that along with natural currents produced by winds and/orwater temperature differences, has the capacity of generating a waterdissipation pattern of the volume of water contained in dissipation zone2 into the sedimentation zone 1, and wherein the dissipation zone 2 isarranged and configured to allow a Contamination Reduction Index (CRI)of up to 30 minutes.
 2. Method according to claim 1, wherein thesedimentation zone 1 and the dissipation zone 2 are delimited bydelimitation means (4).
 3. Method according to claim 2, wherein thedelimitation means (4) is selected from the group comprising: a visualdelimitation, a flotation line, a delimitation line, overhead flags,buoys, a slope change, different depth and combinations thereof. 4.Method according to claim 2, wherein the delimitation means (4) isestablished by means of a brochure, designations by signage or rules, ahandbook, a user guideline and by written and/or verbal instructions,among others.
 5. Method according to claim 1, wherein the sedimentationzone 1 has a depth of at least 1.8 meters at its deepest point, whereinan efficient depth for settling of the microorganisms and contaminantsis established and disturbance from bathers is minimized.
 6. Methodaccording to claim 1, wherein the sedimentation zone 1 has a surfacearea of at least 1,500 m², preferably at least 6,000 m² and even morepreferably of at least 10,000 m².
 7. Method according to claim 1,wherein the flocculant composition comprises one or more flocculantsagents selected from the group including synthetic polymers, quaternaryammonium cationic polymers, polycationic polymers, aluminum salts,calcium oxide, calcium hydroxide, and mixtures thereof.
 8. Methodaccording to claim 7, wherein the flocculant agents are selected fromthe group comprising a cationic or anionic polymeric flocculant andmixtures thereof.
 9. Method according to claim 1, wherein the flocculantcomposition is added to the sedimentation zone 1 at least once every 7days at a rate of 0.03 g to 3.0 g per m³ of volume of water contained inthe sedimentation zone
 1. 10. Method according to claim 1, wherein aperiodic cleaning of a bottom surface of the sedimentation zone 1 isperformed, whereby the sedimentation zone 1 will have a more naturalaspect such as natural lakes and lagoons and daily cleaning is notrequired.
 11. Method according to claim 10, wherein the bottom surfaceof the sedimentation zone 1 is cleaned at least once every 7-daysperiod.
 12. Method according to claim 1, wherein the sedimentation zone1 is designed to discourage bathers from entering the sedimentation zone1, whereby direct contact recreational purposes are minimized and thepractice of aquatic sports with secondary contact purposes isencouraged.
 13. Method according to claim 1, wherein the dissipationzone 2 is designed so that it has a depth of up to 1.4 meters at itsdeepest point.
 14. Method according to claim 1, wherein the dissipationzone 2 is designed so that it has a depth of up to 1.6 meters at itsdeepest point.
 15. Method according to claim 1, wherein the dissipationzone 2 is designed so that it has a depth of up to 1.8 meters at itsdeepest point.
 16. Method according to claim 1, wherein the dissipationzone 2 comprises a downward slope from a periphery 12 to the bottomsurface at an angle a that results in a slope of up to 15% to achieve asafe entry to the large water body
 3. 17. Method according to claim 1,wherein the dissipation zone 2 is designated so that as a daily average,at least 90% of the total number of bathers within the large water body3 is present in the dissipation zone
 2. 18. Method according to claim 1,wherein the dissipation zone 2 is designed to have a maximum density ofbathers of one bather per two square meters.
 19. Method according toclaim 1, wherein the dissipation zone 2 is designed to have a maximumdensity of bathers of one bather per six square meters.
 20. Methodaccording to claim 1, wherein the dissipation zone 2 is designed to havea maximum density of bathers of one bather per eight square meters. 21.Method according to claim 1, wherein the water provided to thedissipation zone 2 through the one or more inlet nozzles 26 is treatedwith ultraviolet light (UV).
 22. Method according to claim 1, whereinthe location, design and configuration of the one or more inlet nozzles26 can vary to achieve different types of water renewal patterns withinthe dissipation zone
 2. 23. Method according to claim 1, wherein thedissipation zone 2 is arranged and configured to establish aContamination Reduction Index (CRI) of up to 25 minutes.
 24. Methodaccording to claim 1, wherein the dissipation zone 2 is arranged andconfigured to establish a Contamination Reduction Index (CRI) of up to20 minutes.
 25. Method according to claim 1, wherein the dissipationzone 2 is arranged and configured to establish a Contamination ReductionIndex (CRI) of up to 15 minutes.
 26. Method according to claim 1,further comprising applying a periodic cleaning of a bottom surface ofdissipation zone 2 in order to maintain the bottom surface of suchdissipation zone 2 free of particles that may generate an aesthetic,safety, or sanitary impact in the water.
 27. Method according to claim26, wherein the bottom surface of the dissipation zone 2 is cleaned atleast once per every 72-hours period.
 28. Method according to claim 1,wherein the permanent chlorine residual is maintained in the dissipationzone 2 by the addition of chlorine tablets, by applying diluted chlorinethrough the one or more inlet nozzles 26 located in the dissipation zone2, or by manually adding chlorine to such zone.
 29. Method according toclaim 1, wherein the large water body 3 comprises a plurality ofseparate dissipation zones 2, preferably located in a periphery 12 ofthe water body
 3. 30. Method according to claim 1, wherein the largewater body 3 has a volume of up to 50.000 m3 and comprises a centralizedfiltration system that can filter the complete water volume of the waterbody.
 31. Method according to claim 1, wherein the permanent chlorineresidual in the dissipation zone 2 is maintained by adding disinfectantagents selected from the group comprising chlorine, bromine, ozone, itsderivatives and mixtures thereof.
 32. Method according to claim 1,further comprising adding an efficient amount of a chlorine disinfectantin the sedimentation zone to maintain a permanent free chlorine level inthe sedimentation zone, preferably of at least 0.5 mg/L.
 33. Methodaccording to claim 1, wherein the Contamination Reduction Index (CRI) isthe time required for the dissipation zone 2 to dissipate a tintedsolution added to the dissipation zone 2 such that the tinted solutionis not visually detectable in the dissipation zone
 2. 34. Methodaccording to claim 1, wherein the Contamination Reduction Index (CRI) isthe time required for dissipation zone 2 of 144 meters cubed todissipate 7 Liters of a tinted solution comprising 30 g/L of carmine and77 g/L of NaC1 out of the dissipation zone 2 such that the tintedsolution is not visually detectable.
 35. Method according to claim 1,wherein the CT index requires a concentration of the disinfectant agents(C) determined in mg/L and a time (T) determined in minutes.